This invention relates to joining heat sealable components using vibratory energy, particularly to the ultrasonic welding of thermoplastic covers and containers of an electrochemical cell or battery.
Ultrasonic welding has been used to assemble thermoplastic battery components together, as taught for instance, in U.S. Pat. Nos. 3,775,189 and 3,981,759. The ultrasonic welding technique as applied to sealed cylindrical electrochemical cells illustrated in FIGS. 1-4, and hereinafter described more fully, is also known to Applicants. However, these prior methods suffer from one or more drawbacks, especially with respect to misalignment of the components, excess flashing of the melt, required use of clamping, and insufficient and non-uniform fusing of the parts together, all of which lead to the production of an unacceptably high percentage of "leakers". These problems have been found to be particularly prevalent when joining crystalline polymers, particularly polypropylene, into an hermetically sealed joint for containment of the electrolyte.
Additional prior art known to Applicants includes Branson Technical Information Bulletin PW-3, printed 5/78.